midterm Flashcards
what is species richness
number of species in a defined region
how does species richness respond with increased area
it increases
where is species richness the highest
tropics
what is a driver
factors that may explain changes in biodiversity
what is a predictor
environmental variables that can be measured and correlated with diversity back to drivers
what is genetic diversity
hoe much genetic variation there is in a population
what is functional diversity
component of diversity that influences ecosystem dynamics, stability, productivity, nutrient balance, and other aspects of ecosystem functioning
what is phylogenetic variation
how much distinct evolutionary history is present in a community
what is alpha diversity
number of species found at a local site
what is gamma diversity
measure of species richness in a region
what is beta diversity
a measure of the difference in species composition or turnover between two or more habitats or local sites in a region
what is a region
large in spatial scale and containing many habitats and communities
what is a biogeographic region / realm
biologically and climatically distinct regions at major geographic boundaries
what is a regional species pool
species likely to colonize a local community
how does a more uneven distribution of abundance affect alpha and beta
alpha decrease
beta increase
how do spatially clumped individuals within a species effect alpha and beta diversity
alpha decrease
beta increase
how does a higher gamma diversity effect beta and alpha
increase both
how does a smaller plot area effect alpha and beta
alpha decrease
beta increase
how does a higher density of individuals influence alpha and beta
alpha increase
beta decrease
factors that change alpha and beta diversity
how uneven the distribution is
if the individuals of a species are clumped or spatially random
total regional gamma richness
density of individuals across the region
what is a driver
factors that may explain patterns in diversity
what is a predictor
environmental variables that can be measured and correlated with diversity and related back to drivers
what is a mechanism
process that lead to the pattern
what is evapotranspiration
the sum of evaporation from the land surface plus transpiration from plants
shows how much primary productivity
what is diversification
speciation - extinction = diversification
how does species richness change as area increases
it increases
what are the hypotheses of the latitudinal diversity gradient
- null model
- ecological hypothesis
- historical hypothesis
- evolutionary hypothesis
what is the null model hypothesis of ldg
mid domain effect: ranges random and more likely to overlap in middle
what is the ecological hypothesis of ldg
climate sets limits for species richness
what is the historical hypothesis of ldg
- area: tropics have more area
- larger areas can support larger populations = less extinction
- larger areas have more barriers = more speciation
-time integrated area hypothesis: tropics have suffered fewer harsh climatic events so they have had more time to speciate
what is the evolutionary hypothesis of ldg
- climate stability hypothesis: tropical climate is predictable and mild allowing for greater speciation and smaller niches = more species
while higher latitudes have unpredictable climates creating larger niches = less species = more extinction - evolutionary speed theory : higher temperature and solar radiation = more mutations and faster growth rate = faster speciation rate
- biotic interactions hypothesis: biotic factors have a stronger selective force than abiotic factors
what is tropical niche conservatism
tendency of lineages to originate in tropics and to remain tropical due to the relations of climatic niches over evolutionary time
why does species richness increase with larger areas
larger areas have more habitats/niches/diversity so can support more species
larger areas can also support more genetic variation, reduce the chances of a catastrophic event from wiping out the populations, larger area= larger target (more colonization)
what is the target effect
bigger area= more colonization
what is the rescue effect
isolation influences extinction
more colonization/immigrants increase the fitness of an island
what is the small island effect
below a certain point species stop obeying the species richness to area relatioonship
what factors effect z
island vs mainland: isolation
dispersal distance of taxonomic group
latitude
how does z effected when its on an island vs mainland
higher on islands
how is z effected by dispersal ability
lower in species with greater ability to disperse
how is z effected by ldg
higher in tropics
what relationship does z have with dispersal abilities
inverse 1
what are stabilizing mechanisms
spatial variantion in environment and resource partitioning
temporal variation
competition - colonization tradeoff
predators
what is spatial variation in the environment/ resource partitioning
species have a preference for certain habitat/environmental conditions
often the species that preform best in optimal conditions are least tolerant
species can forage in different parts of same area (ex: foraging in different parts of tree)
what is temporal variation
seasons changing in environment effect the available nutrient levels as well as how they’re dispersed
certain species are better/worse at certain nutrient levels
storage effect
what is the storage effect
environmental fluctuations effect one species (with lower abundance) disproportionately
though as its density decreases the competition decreases
what is the competition- colonization prediction
how species that are better at colonizing are less competitive
and more competitive species are slower at colonizing
what is a fugitive species
good at colonizing but not as competitive
how can predators stabilize prey populations
preying on most competitive species (ex:starfish example)
prey- switching (ex generalists)
what is a gleamer
out compete at low nutrient levels
what is an opportunist
out compete at higher nutrient levels
what is interference competition
occurs directly between individuals
individual directly alters the resource attaining behaviour of another individual
what is exploitative competition
indirect
use of resources by one individual decreases amount available for others
what is competitive exclusion principle
two species with identical niches cannot coexist indefinitely
what is the law of limiting similarity
the existence of a maximum level of niche overlap to allow for continued coexistence
what is interspecific competition
competition between individuals of different species
what is intraspecific competition
competition between individuals of same species
when is coexistence possible?
when intraspecific competition is greater than interspecific competition
what is R*
minimum equilibrium resource level required to maintain a population
can 2 species coexist if resource levels are constant
no, species with lower r* wins
is coexistence possible if resource levels fluctuate
yes
does coexistence require tradeoffs
yes
what do organisms try to feed on
most profitable food source
what are more efficient specialists or generalists
specialists
what is optimal foraging theory
predators adjust their behaviour in response to variation in prey abundance
What are consumptive effects
lethal effects
occur when predator feeds directly on prey
what are non-consumptive effects
behavioural changes in prey in response to predation
what are examples of non consumptive effects
changes in morphology
changes in behaviour
changes in life history (ex timing of metamorphosis)
changes in stress levels
why do changes in response to prey have tradeoffs
investments in defence cannot be used for reproduction
changes in foraging behaviour may have foraging costs
what determine how predators influence a community
predator preferences and competitive ability of prey
what is a functional response
change in predation in response to changing prey density
individual response
what is a numerical response
change in reproductive rate with changing prey density
population response
what are faster functional or numerical responses
functional
what is a type one functional response
linear increase in consumption rate as food densities rise until reaching a maximum consumption rate
slope = consumer’s attack rate
what is a type 2 functional response
rate of prey consumption rises as prey density increases, though eventually plateaus where rate of consumption remains constant, no matter the increase in prey density
reaches saturation gradually unlike type one which is linear
what is a type 3 functional response
occur when predators increase their activity with increasing prey, eventually plateauing as prey densities start to decline
what type of functional response do generalists have
type 3
what type of functional response do specialist predators have
type 2
what is a carrying capacity
K
maximum population size supported by the available resources in an environment
what is a specialist
predator that feeds on a single prey type
what is a generalist
predators that switch between prey types
what does Lotka Volterra model assume
prey populations grow exponentially
type 1 functional response
predator growth is independent of predator density
what does Lotka Volterra model show
simplest model describing population dynamics of a single predator species feeding on a single prey species
produces coupled cycles in predator prey relationships but is very unstable
what is the rosenzweig MacArthur model
incorporates carrying capacity into prey population of Lotka Volterra to make it more realistic type 2 response which makes isocline be humped
what does it mean of predator prey intersect is to the left of isocline
system changes can result in one or both species going extinct
what does it mean of predator prey intersect is to the right of isocline
system will return back to equilibrium after deviation
what is an aggregative response
immigration and emigration rates
what is a demographic response
reproduction and mortality rates
what does aggregative + demographic responses =
numerical response
what is the paradox of enrichment
increasing prey’s carrying capacity will decrease stability of predator prey dynamics
when are predator prey systems most stable
when predator is inefficient
what is a grinnellian niche
the habitat requirements that allow a species to persist and reproduce
what is a hutchinsonian niche
expanded grinellian niche by separating habitat into specific resources
and considered how species interact
what is a eltonian niche
an animals place in the biotic environment
ex: its relation to food and enemies
what is a sequential breakage hypothesis
available niche is slowly divided among species as they arrive
what is a broken stick model
all species arrive at same time and resources are divided randomly
what is a geometric series
each successive species takes up a fixed fraction of available niche space
